Experimental data shows that in order to maximize the implosion 

 strengths of the spherical buoys, the hemispheres should be fused if the 

 construction material is glass, or should rely on a fabrication method 

 that produces monolithic hulls if the material is alumina ceramic. Using 

 such assembly methods, Pyrex spheres can be expected to withstand at least 

 120,000 psi and AD-99C alumina ceramic spheres at least 300,000 psi com- 

 pressive stress in the hull prior to implosion. The use of joints with 

 or without gaskets with either one of the materials invariably lowers 

 the implosion pressure of the buoys. Although different gasket materials 

 have been experimented with, the buoys with beveled hand- lapped joints 

 without gaskets have shown to have the highest resistance, in some cases 

 approaching the strength of fused or monolithic buoys. Gasketless joints 

 with beveled and hand- lapped surfaces in 99-percent alumina ceramic buoys 

 withstood between three to four times higher compressive stresses than 

 Pyrex buoys. 



In addition to commercially available items, there are various custom- 

 made items which have proven interesting in experiments. Chemically 

 strengthened glass spheres, fabricated from Pittsburgh Plate Glass' Hercu- 

 lite II strengthened glass and Corning Glass Works' Chemcor strengthened 

 glass, have been found capable of withstanding somewhat higher compres- 

 sive bearing stresses than semi- tempered or annealed Pyrex spheres. Also, 

 custom-made spheres of Corning Glass Works' Pyroceram #9506 have been 

 found to withstand approximately the same compressive bearing stresses in 

 a lapped ceramic to ceramic joint as the alumina ceramic. 



At the present time, the commercially available glass and ceramic 

 buoys are of small diameter, but development is being carried on at glass 

 and ceramic industry research facilities which will result in the immedi- 

 ate future in buoys of up to 4 feet in diameter with 20, 000- foot depth 

 capability. Such larger buoys will probably also permit lowering of the 

 price per pound of buoyancy. The current price for Pyrex buoys purchased 

 in small lots is $5 per pound of buoyancy, and for such buoys bought in 

 large lots, the price is $2,50 per pound of buoyancy. The lowered price ■ 

 should reach approximately $2 per pound of buoyancy in 1000-pound buoy- 

 ancy Pyrex spheres. In comparison, alumina ceramic buoys are currently 

 selling for approximately twice that of Pyrex spheres, but improving mass 

 production techniques promise to bring these buoys in line with prices 

 for Pyrex spheres. 



With the increased availability, larger diameter, and lowered price, 

 glass and ceramic buoys (which already surpass metallic, glass-fiber epoxy, 

 and syntactic foam buoys on a buoyancy basis) will also become competitive 

 on cost per pound of buoyancy basis. It appears that the future of glass 

 and ceramic in the deep submergence buoy field is assured as economical 

 structure materials without peer in compressive strength. 



260 



